Focusing device for sound recorders



July 6, 1937. M. E. COLLHNS 2,035,900

FOCUSING DEVICE FOR SOUND RECORDERS Filed March 21, 1936 INVENTOR M/L FOED E. COAL/N5 AT 0 NEY Patented July 6, 1937 sifiTEld'l @EFMZE to ticn of Delaware .aadio Corporation of America, a corpora- Applicatien March 21, 1936, Serial No. 70,6ill9 2 Glaims.

This invention relates to a focusing device for determining the accurate focus of a sound recording optical system in sound recorders and particularly the type of sound recorders incorporated in motion picture cameras.

It is customary in certain types of motion picture cameras for certain purposes such as new reel recording, etc, to include sound recording mechanism in the camera. In one type of cam-- era, 1. e., that known as the Akcley, the sound recording optical system is bin t into the camera and an attachment is placed at the rear of the camera comprising a number of rollers over which the film runs after leaving the picture gate. Due

to the mechanical arrangement of the parts it has heretofore been extremely difficult to properly focus the optical system upon the film at the sound recording point as the optical system. being on the interior of the camera, is not readily accessible for viewing.

One object of this invention to provide a central means for focusing the recording beam in such a device.

Another object of my invention is to provide a focusing device which can be readily attached to or removed from the camera.

Another object of my invention is to provide such a focusing device which will not interfere with the normal operation of the camera.

Another object of my invention is to provide such a focusing device which may remain attached to the camera during operation.

Other and incidental objects of invention will be apparent to those skilled in the art from do a reading of the following specification and an inspection of the accompanying drawing in which,

Figure 1 is a front view of the film roller in focusing position.

Figure 2 is a front view of the roller shaft,

Figure 3 is a longitudinal section of the apparatus in focusing position.

As shown in Fig. 3 the film handling system for the sound recording includes a casing member Ill which carries the rollers i3 and M.

5 In cooperative relation with the film adjacent to roller i2 is located a sound recording optical system the end of which is indicated at and which images the light upon the film at it at which point the focusing is to be determined.

In the performance of my invention I provide the roller i2 with a groove il underneath the sound track area and the entire width. thereof. In alignment with this groove ii and the sound track I provide in the roller a diametral hole [8 of the same size as the width of the sound (Cl. Nil-JAWS) track. As shown in Figure 2 the shaft for the roller is provided with an enlarged portion at is and through this enlarged portion there is provided a hole 26.

When the shaft i9 is installed in the camel. it is arranged with hole in alignment with the optical system and it will be apparent that when the roller i2 is rotated to the proper position the holes l 8 and 253 will be in alignment permitting inspection of the image on the film from the opposite side of the roller.

On the outside of the casing it, I provide a mounting ring 28 secured to the casing by screws 22 and this ring is interiorly threaded indicated at 23. includes an end member 2 which is threaded to fit the member 2 land which carries an appropriate objective 25. This member also includes a tube 26 into which the eyepiece tube El, fitted with appropriate lenses 28, slides. The focal length of the lens 35 is of course so chosen as to properly image the line of light on the film at the point 55 for magnification by the eyepiece lenses 28.

It will be apparent that if it is desired to leave this focusing device on the camera while in operation the eyepiece 28 may be capped or the eyepiece may be removed and the tube may be capped. Alternatively the entire focusing device may be unscrewed from the member 2 l an opaque plate plug screwed into the aperture to prevent fogging of the film by light admitted through the holes l8 and 28.

Having now described my invention I claim:

1. Sound recording apparatus comprising a recording optical system, a roller arranged to support a record strip at the recording point and provided with an aperture in alignment with the record area of said strip and adapted to be aligned with said recording optical system, and focusing means including a viewing microscope in alignment with said aperture.

2. Sound recording apparatus comprising a recording optical system, a roller arranged to support record strip at the provided with an aperture in alignment with the record area of said strip and adapted to be aligned with said recording optical system, a shaft supporting said roller and provided with an aperture in alignment with said recording optical system adapted to register with the aperture in the said roller, and focusing means including a viewing microscope in alignment with said apertures.

MILFORD E. COLLINS.

A focusing microscope is provided which recording point and 

